Avian Metapneumovirus Infection Rhinotracheitis (Swollen Head Syndrome SHS) in Laying Hens
The Avian metapneumovirus infection has been associated with the swollen head syndrome (SHS) in chickens, which is characterized by the following clinical signs: swelling of the periorbital and infra-orbital sinuses, torticollis, cerebral disorientation and opisthotonus, as a result of secondary E coli infection. Usually, less than 4% of the flock are affected, although, widespread respiratory signs are usually present. Mortality rarely exceeds 2%. The infection is associated with reduced egg production loss the shell colour and misshapen eggs.
Avian Metapneumovirus infection in chickens is less clearly defined and may not always be associated with clinical signs. The virus in chickens has been associated with the swollen head syndrome (SHS) in chickens. There is evidence that infectious bronchitis virus together with E. coli may also associated with SHS.
Observed Clinical Signs Happenings
Visibly sick birds
- Few visibly sick birds
- Usually, less than 4% of the flock are affected
- Egg production drops gradually
- Egg production may be affected
- Low mortality or increases gradually
- Mortality rarely exceeds 2%
- Skinny body (Poor body fleshing condition)
- Respiratory signs spread fast
- Widespread respiratory signs are usually present
As a result of secondary E. coli infection
- Cerebral disorientation
Head Comb Wattles Face Nostrils Sinuses Mount Beak Earlobes
- Swelling of the Head
- Swelling of the periorbital and infraorbital sinuses
Body Parts (Neck wings breast abdomen shanks legs hocks feet joints vent skin)
- Hens in lay may also present with prolapsed oviducts due to violent coughing
- Pale or loss of colour in brown-shelled eggs
- Misshapen eggs
Avian Metapneumovirus Infection Rhinotracheitis (Swollen Head Syndrome SHD) in Laying Hens DOES NOT exhibit or manifest any of the following clinical signs happenings:
- Egg production declines rapidly
- High mortality or increases rapidly
- Dead birds in Good Body fleshing condition
- Many visibly sick birds
- Flock behaviour activity change
- Droppings abnormalities
- Respiratory signs spread slow
- Lameness or unusual movements, incoordination, ataxia
- Eyes abnormalities
- Feathers abnormalities
- Feed Consumption Changes
- Internal Egg defects
- Causing Agents
- Avian metapneumovirus infection. Avian Metapneumoviruses are members of the subfamily Pneumoviridae, belonging to the family Paramixoviridae
- Affected Systems/Organs
- Respiratory, Reproductive and Neurological System
- Transmission is rapid through aerosols via the respiratory route. Transmission from parents is uncertain. Contaminated objects.
- Mainly Affects
- Egg production, Egg quality and Liveability
- Control respiratory stressors. Multivitamins. Good management practices. Good biosecurity.
- Suggested Actions
- Can be confirmed with clinical signs and gross lesions
- Can be managed with feed additives, off-the-shelf medications
- Diagnosis should be confirmed with rapid assays and/or a certified laboratory
- Veterinary intervention is recommended
Impact on Egg quality
Impact on Liveability
Impact on Production
Overall Economic Impact
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David E. Swayne. 2013. Diseases of Poultry 13th Edition. page 115
Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition.
Paul McMullin. 2004. A pocket Guide to Poultry Health and Disease. First Edition.
Steven Leeson, John D. Summers. 2008. Commercial Poultry Nutrition. Third Edition.
Donald D. Bell, Williams D. Weaver. 2009. Commercial Chicken Meat and Egg Production. Fifth Edition.